1.) Open up iTunes and login to your iTunes account.
2.) Once you are logged in go back to the iTunes store home page.
3.) In the top right hand corner under “Quick Links” the first link you will see is “Redeem” click on this.
4.) Once you have clicked on the Redeem link you will then be prompted to enter in your iTunes Gift Card code. Insert the code in the provided box.
5.) After you have your code typed in click on the Redeem button and you now have your funds in your iTunes account!
Here is a video tutorial on how to redeem your iTunes Gift Card